Investigation of low-temperature cracking resistance of asphalt mixtures by conducting Disc-Shaped Compact Tension (DC(T)) and Semi-Circular Bend (SCB) tests

Abstract

This research was focused to investigate the low-temperature cracking resistance of five plant produced SP12.5 surface course asphalt mixtures by conducting the Disc-Shaped Compact Tension (DC(T)), Semi-Circular Bend (SCB) and Bending Beam Rheometer (BBR) tests. The DC(T) and SCB testing were conducted at three temperatures, −18, −24 and −30℃, to characterize the cracking resistance and determine the mixture-based low-temperature Performance Grade (PG) of asphalt mixtures by using the suggested minimum threshold values of DC(T) fracture energy. Moreover, BBR testing was conducted on the recovered asphalt binders from the same asphalt mixtures. The analysis of tests results showed that the DC(T) and SCB fracture energies at three temperatures were statistically comparable and characterized the low-temperature cracking resistance similarly. Even though, the low temperature PG of the recovered asphalt binders were within the Superpave specifications, in some cases, they were mismatched with the mixture-based low-temperature PG. Dissimilar to the SCB fracture energies, the DC(T) fracture energies had better relationships with the low-temperature properties of the recovered asphalt binders. Considering the low-temperature PG of the recovered asphalt binders and the mixture-based low-temperature PG, the DC(T) and SCB tests are essentially needed to reliably evaluate the low-temperature cracking resistance of asphalt mixtures. Moreover, the relationships between the DC(T) fracture energies and the recovered asphalt binder properties revealed that there was a better correlation between the DC(T) fracture energies at three testing temperatures and the recovered asphalt binders’ temperatures corresponding to the stiffness value of 300 MPa.